When processing silicon wafers, a good product requires surface uniformity. Achieving surface uniformity, etch, clean and/or preclean processes are implemented to remove semiconductor materials, dielectric materials and/or metallic materials. Usually, an etching process uses various reactants and/or plasmas to remove semiconductor materials and generated byproducts. The reactants and byproducts may undesirably condense, forming particles within the etch processing chamber. The particles and/or byproducts formed within the processing chamber may adversely affect surface uniformity of the substrates.
For a conventional etch apparatus, a pedestal is configured to support a wafer within an etch chamber for an etch process. The pedestal has a sealing band at the edge of the pedestal for contacting with the substrate. A cooling water flows through the pedestal for cooling the pedestal, such that etchants can deposit on the wafer. The pedestal also has a plurality of chucking holes surrounded by the sealing band. During an etch process, a gas is exhausted through the chucking holes to chuck the substrate with the pedestal. After the substrate is dechucked and lifted from the pedestal, the sealing band is exposed to the etchants and/or byproducts of the etch process. The etchants and/or byproducts are prone to condensing on the sealing band disposed at the edge of the pedestal due to the cooling effect by the cooling wafer flowing through the pedestal. When another wafer is chucked on the pedestal to be etched, the condensing byproducts and/or particles on the sealing band may tilt the substrate, resulting in a non-uniform etch to the wafer.